Various types of data retransmission methods can be used to ensure certainty of data transmission to a receiving side in a wireless communication system. Particularly, the need to use a retransmission method increases when the receiving side should necessarily receive non-real time packet data such as signaling data or TCP/IP data.
An example of the data transmission method used in the wireless communication system will be described as follows. The receiving side transmits a status report to a transmitting side to report whether at least one or more data blocks transmitted from the transmitting side have been successfully received or not. The transmitting side retransmits data blocks which the receiving side has failed to receive, to the receiving side based on the status report. For application of the retransmission method, data which have been transmitted once should be stored in a buffer for a certain time period without discarding so as to prepare retransmission. Accordingly, transmission buffer and a retransmission buffer are required, wherein data which have never been transmitted to the receiving side are stored in the transmission buffer and data which have been transmitted to the receiving side but need to be on standby for retransmission are stored in the retransmission buffer.
The transmitting side can request the receiving side to transmit the status report. This procedure is referred to as a polling procedure. If the status report transmitted from the receiving side is lost during transmission or the receiving side does not transmit the status report to the transmitting side timely, the transmitting side can perform the polling procedure. Alternatively, the transmitting side can perform the polling procedure periodically.